Many supported components are connected to a support frame through some sort of resilient mounting apparatus. For example, resilient mounting apparatuses are substantially universally used to connect the engine to the frame of a mobile vehicle to isolate engine generated vibrations and noises from the rest of the vehicle. As would be expected, such resilient mounting apparatuses take on many shapes, styles, sizes, and so forth, depending upon the application and the functional specification of the particular usage.
Two of the more important aspects of any resilient mounting apparatus design are the cost and size which generally go hand in hand since size dictates the amount and type of material used, construction techniques, and so forth, which contribute to the total cost of building the mounting apparatus. The size is generally determined by the available space between the engine and support members and in recent years has become decreasingly smaller. However, regardless of the size and cost, the mounting apparatus must provide proper vibration and/or noise isolation while providing proper deflection control. Moreover, the resilient mounting apparatus must have high fatigue capabilities for long life.
One example of the many styles of resilient mounting apparatuses is commonly referred to as a "mushroom" mounting apparatus. Most of such mounting apparatuses are symmetrical in design and have an annular resilient elastomeric primary support pad between the supporting and supported members and identical annular resilient elastomeric rebound pad on the other side of one of the members with each of the pads having a tubular portion extending into a common hole in either the supporting or supported member. A disadvantage of those mounting apparatuses is that generally the capability of the rebound pad need not be as great as the capability of the primary pad. Thus, by using identical parts for both the primary and rebound loading, the rebound pad is generally over designed for its function and adds significantly to the overall cost of the mounting apparatus. Moreover, providing the tubular projection on both parts also adds to the cost of the mounting apparatus.
One desirable feature used in some of the mushroom style mounting apparatus includes providing an annular air space between the cylindrical portions and a rigid spacer sleeve extending through axially aligned passages in the support and rebound pads. The air space provides a dual spring rate deflection capability in the radial or lateral direction. The heretofore known mounting apparatus did not have any problem of sealing the air space to prevent dirt from migrating into the air space. However, by reducing the amount of material in the mounting apparatus to a minimum and minimizing the use of costly manufacturing techniques, the resilient rebound pad of the present mounting apparatus sometimes separates from the mating supporting or supported member during high loading of the primary support pad. This would permit dirt or other foreign matter to migrate into the air space. Over a period of time the air space would fill up and greatly reduce the dual rate capability.
The present invention is directed to overcoming one or more of the problems as set forth above.